Many of the non-histone proteins that are readily seen by electrophoresis are structural rather than regulatory proteins. Some are contractile proteins, some are nuclear matrix proteins, some are RNA associated proteins and many are unidentified. The question this grant asks is: "What is the relationship between these structural non-histone proteins and highly or moderately repetitious DNA? Do some of these proteins specifically bind to certain repetitious sequences and thereby play a role in chromosome structure, condensation, heterochromatinization, or gross gene regulation?" These questions will be approached by several techniques. (1) DNA/DNA competition filter binding assays. Here, the ability of various non-histone and contractile proteins to preferentially bind H3-mouse as opposed to C14-E. coli DNA will be tested to determine if there are specific binding sites for these proteins in mammalian DNA. (2) Affinity chromatography. Here, mouse satellite, main band, GC-rich, and AT-rich DNA and DNA of various degrees of repetitiousness will be used to determine if some non-histone proteins have preferential affinity for certain types of DNA.